I am going to swap out the opamps in my Music Hall CD25 player. I know the 627's work in this player (with BrownDog adapter and 2 chips), but was wondering about the 637's, as I can get a much better price on compared to the 627's. Or would a discrete opamp, like this one work out better? www.bursonaudio.com/burson_hdam_module.htm ?

Any and all help would be greatly appreciated!

Thanks,
Dan

Epicurean

11th January 2007 11:53 AM

I would say no. I doubt your CD-player has a high gain and the OPA637 needs a minimum voltage gain of 5 whereas the OPA627 is stable at unity gain. I have OPA637s in my headphone amp and a gain of 6 was too low so I raised it to 10 and now its working fine.

Tried 2 OPA637APs per channel on my Rotel RCD-02 and it didn't work too well either. There's quite a bit of noise which I think is due to oscillation.

You might want to try the LM4562s if you can get hold of them. General opinion is that it's better than the OPAs.

Regards
CK

marchewd

12th January 2007 08:21 AM

Thanks

Thanks for the replies. What about using the 637's in either a Jolida JD-9 phono pre or Rogue Stealth phono pre?

Thanks,
Dan

musicfan_cbs

12th January 2007 09:08 AM

In my opinion OPA627 is a better/safer choice (although more pricey). It is a lot easier to integrate that 637 (-->>voltage gain) and from what I've heard so far yields a bit better sonic results (in both cd-players and preamp stages).
I think you should at least buy a pair of opa627 and compare the results.